1. Field of the Invention
The present invention relates to a compound useful as an intermediate for a dye releasing redox compound which is suitable for use in the color diffusion transfer process and, more particularly, to a compound useful as an intermediate for a dye releasing redox compound having an improved transferability and light fastness.
2. Description of the Prior Art
Color diffusion transfer color image forming processes using a dye releasing redox compound are described in U.S. Pat. Nos. 3,928,312, 3,931,144, 3,929,760, 3,932,381, 3,954,476, U.S. Patent Application Document B-351,673, West German Patent Application (OLS) 2,505,248, and Research Disclosure, No. 13024 (1957). The term "dye releasing redox compound" means a compound containing therein a group referred to as a redox moiety and a dye (including a dye precursor) moiety. The redox moiety renders the redox compound immobile due to a ballast group attached thereto, but the compound per se splits and releases a compound having the dye moiety (dye compound) due to a redox reaction under alkaline conditions. For instance, a light-sensitive element having a light-sensitive silver halide emulsion layer and a redox compound associated therewith is exposed and developed with an alkaline processing solution, whereby the redox compound per se is oxidized in proportion to the amount of developed silver halide and then splits into a compound having a dye moiety (dye compound) and a nondiffusible quinone compound due to the alkaline processing solution. As a result, the compound having a dye moiety diffuses into an image receiving layer to provide a transferred image therein.
Examples of redox compounds which release cyan dye compounds are described in U.S. Pat. Nos. 3,929,760 and 3,942,987, etc. Examples of redox compounds which release magenta dye compounds are described in U.S. Pat. Nos. 3,954,476, 3,931,144 and 3,932,380, etc. Examples of redox compounds which release yellow dye compounds are described in U.S. Pat. No. 4,013,633, etc. However, using these prior art dye releasing redox compounds, technical problems are encountered in that the transferred images have insufficient stability (for example, the light fastness of the images is not sufficient and the images fade to a large extent under light) and in that the transfer of the dye compounds is not sufficient.
The insufficient transferability and light fastness of the dye compound result from the structure of the redox moiety in the redox compound. That is, a typical known redox moiety is an o- or p-hydroxyarylsulfamoyl group having a ballast group. On the contrary, it was found that when a redox compound in which an aminosulfonyl (sulfamoyl) or aminocarbonyl (carbamoyl) group substituted with a phenyl group to which an alkoxy group and a known redox moiety are bonded at the para position and the meta position, respectively, is used as a redox moiety, a markedly improved transferability and light fastness is achieved in the dye compound.